AB0775 EFFECTIVENESS AND SAFETY OF NON-MEDICAL SWITCH FROM RITUXIMAB ORIGINATOR TO AND AMONG BIOSIMILARS IN SMALL VESSEL VASCULITIDES PATIENTS: REAL WORLD DATA FROM A RETROSPECTIVE MONOCENTRIC STUDY
Authors: S. Stano, L. Coladonato, A. Capuano, M. Lavista, V. Spedicato, M. Fornaro, F. Iannone, F. Cacciapaglia
Journal: Annals of the Rheumatic Diseases (2023)

<h3>Background</h3> Rituximab (RTX) is indicated for treatment of severe small vessel vasculitides (SVV), namely granulomatosis with polyangiitis (GPA) microscopic polyangiitis (MPA) and cryoglobulinemic vasculitis (CV). Currently available RTX molecules include the originator drug (RTX-Or) and two biosimilars, CT-P10 and GP2013. SVV are rare and only few studies evaluated safety and efficacy of non-medical switch (NMS) from RTX-Or to CT-P10 <sup>[1,2,3]</sup>. No data are available about clinical use of GP2013 and switching strategies between RTX biosimilars in these conditions. <h3>Objectives</h3> The aim of our study was to obtain real world data about effectiveness and safety of different RTX molecules, and to evaluate switching strategies from RTX-Or to and among biosimilars for treatment of patients affected by GPA, MPA and CV. <h3>Methods</h3> We retrospectively evaluated clinical and laboratory data of patients affected by GPA, MPA and CV, according to specific classification criteria, and treated with RTX based on expert rheumatologist indication between 2018, date of biosimilars availability, and 2022. Specifically, C-Reactive Protein (CRP), Erythrocyte Sedimentation Rate (ESR), gamma globulins, C3, C4, Five Factor Score (FFS), Birmingham Vasculitis Activity Score version 3 (BVASv3) and concomitant rheumatologic therapy were recorded. Autoimmunity was assessed as anti-neutrophil cytoplasmic antibody (ANCA) positivity for GPA and MPA and as presence of cryoglobulins in CV. All patients were followed-up for at least 12 months and received at least two cycles of therapy with RTX-Or, CT-P10 or GP2013. NMS to RTX biosimilars was performed when clinically feasible and accepted by the patient. Any safety issue associated with RTX treatment was recorded. Clinical and laboratory data were analyzed using appropriate statistical tests with SPSS. <h3>Results</h3> Data on 29 patients (female No. 19 - 65,5%; mean age 56.3±15.7 years old; mean disease duration 52.3±20.1 months) were available. Ten patients started therapy with RTX-Or, and all accepted NMS to CT-P10. Nine patients were treated with CT-P10 and six accepted NMS to GP2013. Twelve patients started treatment with GP2013. At baseline and during follow-up no significant differences among laboratory and clinical data of patients treated with any RTX molecule was highlighted. All patients achieved a statistically significant reduction of mean corticosteroid dose used from 20.4±12.8 mg/day of prednisone equivalents at baseline to 5.0±2.8 mg/day at 12 months (p=0.00016), and of mean BVASv3 from 20.0±4.5 at baseline to 4.7±2.3 after 12 months (p&lt;0.00001). On average, a reduction of CRP and ESR levels, despite a small decrement of gamma globulins level was also observed. Mean C3 and C4 level resulted normal over time. ANCA positive patients decreased from 83.3% at baseline to 35.3% after one year (p=0.0059). Cryoglobulins were still detectable in 36.4% of patients after one year of RTX treatment (p=0.0039). No severe AEs were recorded, and only two CV patients treated with CT-P10 presented mild AEs: moderate lymphopenia, resolved after temporary drug withdrawal in one subject, and mild urticaria after infusion, with no new AEs after CT-P10 retreatment in the other. Of note, no AEs were observed in our cohort after NMS. <h3>Conclusion</h3> Our study demonstrated comparable effectiveness and safety of RTX-Or and its two biosimilars both for induction and maintenance of remission. The effectiveness and safety of NMS for RTX in SVV is confirmed, and our results grant first time evidence for safety and maintained effectiveness of treatment in such patients also after NMS between biosimilars. This practice allows economic sustainability for healthcare systems and represents a hot topic in clinical practice. <h3>References</h3> [1]Antonelou M et al. <i>Scand. J. Rheumatol</i>. (2022) [2]Vacchi C et al. <i>Intern Emerg Med</i>. (2021) [3]Mittal S et al. <i>Clin Rheumatol</i>. (2021) <h3>Acknowledgements:</h3> NIL. <h3>Disclosure of Interests</h3> None Declared.